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Inhaled Colistin PK/PD — SCE Infectious Diseases MCQ

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HardRespiratory InfectionInhaled Colistin PK/PDSCE Infectious Diseases

A bronchiectasis patient receiving inhaled colistin has a resistant Pseudomonas MIC reported but remains clinically stable with fewer exacerbations. What is the best interpretation?

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Correct answer: B — Do not infer automatic clinical failure from the systemic breakpoint alone; review symptoms, exacerbations, adherence and specialist microbiology before changing inhaled therapy with review

The best answer is “Do not infer automatic clinical failure from the systemic breakpoint alone; review symptoms, exacerbations, adherence and specialist microbiology before changing inhaled therapy with review”. Nebulised therapy produces airway exposures not represented by systemic breakpoints, so clinical effect and specialist interpretation matter. “Stop inhaled colistin immediately and give intravenous meropenem indefinitely” does not match the decisive clinical feature or cited guidance. “Refer for transplant solely because the MIC rose” does not match the decisive clinical feature or cited guidance. “Assume inhaled and intravenous colistin have identical airway exposure” does not match the decisive clinical feature or cited guidance. “Label the isolate pan-drug resistant without testing other agents” does not match the decisive clinical feature or cited guidance.

Reference: BTS bronchiectasis guideline: https://thorax.bmj.com/content/74/Suppl_1/1